Published in:
01-12-2017 | Original Article
Error range in proximal femoral osteotomy using computer tomography-based navigation
Published in: International Journal of Computer Assisted Radiology and Surgery | Issue 12/2017
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Purpose
The purpose of this preliminary study was to determine the error range compared with preoperative plans in proximal femoral osteotomy conducted using a computed tomography (CT)-based navigation system.
Methods
Four patients (four hips) underwent transtrochanteric rotational osteotomy (TRO), and three patients (four hips) underwent curved varus osteotomy (CVO) using CT-based navigation. Volume registration of pre- and postoperative CT was performed for error assessment.
Results
In TRO, the mean osteotomy angle error was \(1.1^{\circ }\) (range \(0^{\circ }{-}3.1^{\circ }\)) in the valgus direction and \(1.8^{\circ }\) (range \(0^{\circ }{-}4.3^{\circ }\)) in the retroversion direction. The mean osteotomy position error, with the femoral head side as positive, was −0.4 mm (range −1.4 to 0 mm). The bone fragment rotational movement error was \(2.5^{\circ }\) (range \(0^{\circ }{-}10^{\circ }\)). In CVO, the mean osteotomy position error, with the femoral head side as positive, was −0.2 mm (range −2.0 to 1.7 mm) at the level of the lesser trochanter and 0.8 mm (range 0–3.2 mm) at the level of the greater trochanter. Bone fragment varus accuracy was \(2.3^{\circ }\) (range \(0^{\circ }{-}5^{\circ }\)).
Conclusions
In proximal femoral osteotomy using CT-based navigation, the angle error of osteotomy was within \(5^{\circ }\) and the positional error was within 4 mm. The rotational movement error of the proximal fragment was within \(10^{\circ }\). These margins of error should be considered in preoperative planning. To improve surgical accuracy, it would be necessary to develop a computer-assisted device which can track the osteotomized fragment.